We plan to study glucose metabolism and lipogenesis in isolated hepatocytes of Japanese quail (Coutournix coutournix). This is a continuation of our current studies with liver cells of egglaying quail. These cells have a very high metabolic rate and incorporate lactate extensively into fatty acid. Glucose is a poor substrate for lipogenesis. We discovered that physiological concentrations of alanine and several other amino acids stimulate many fold the uptake of glucose and increase its contribution to fatty acid carbon by 400 to 800%. The amino acids also depress gluconeogenesis from lactate and redirect the carbon flux into fatty acid. Our plans are: (1) to study the mechanism of the amino acid effect to determine its site of action, whether it causes a covalent modification of rate limiting enzyme(s) or whether the amino acids serve as precursors for an allosteric activator; (2) Birds including quail have no pentose cycle, and it is not known how NADPH for fatty acid synthesis is generated. We will determine the source of the reducing equivalents and evaluate the role of malic enzyme and isocitric dehydrogenase for transhydrogenation and NADPH generation; (3) It is generally believed that birds lack a high KM hexokinase (glucokinase). We have established however, the presence of an active glucokinase, with properties different from that in rats. the enzyme is membrane bound. We will determine the nature of the membrane (most likely cell plasma membrane) and will study the kinetics of glucokinase and its regulatory role in glucose uptake. Other enzymes of glycolysis and lipogenesis in quail liver will be examined. (4) To account for the large increase in lipogenesis which accompanies the onset of egglaying, we will compare the profile of glycolytic and lipogenic enzymes in nonlaying and egglaying quail. The kinetics of glucose and lactate labelled with 14C and 3H will be studied in vivo in both types of bird, and the relative contribution of glucose and non-glucose carbon to fatty acids will be evaluated.